Various synthetic roof and wall coverings are known today, such as those formed of elongated thermoplastic panels that are nailed to the wall or roof support surface in horizontal courses or rows in partially overlapping relation to each other so as to provide a substantially water resistant, protective layer over the support surface. Such panels, which usually are identically molded, commonly are formed with a plurality of rows of simulated building elements, such as shake shingles. Because the panels are identically molded, a panel-to-panel identity can be easily noticed if the panels are not carefully installed. Leakage problems between adjoining panels also can occur.
To facilitate installation, such panels typically are nailed to the wall or support surface along an upper horizontal nailing flange with the lower marginal edge region overlapping the panel in the course immediately below and with one side marginal edge region overlapping the laterally adjacent panel. While various means have been proposed for interlocking the overlapping portions of adjacent panels to provide a water seal therebetween and to minimize the noticeability of the junctions between panels, such interlocks often have been cumbersome to engage during installation and frequently are ineffective in establishing and maintaining sealed engagement of the panels, particularly when the panels are mounted on irregular surfaces or are exposed to extreme weather conditions.
Because such panels are made of plastic and are relatively large in size, usually having a length of 48 inches or more, the panels tend to easily bend and deform during handling and upon mounting on even slightly irregular or rough mounting surfaces, which often occurs when the panels are being used as a replacement covering on an existing wall or roof. Deformation and bending of the panels, either as a result of mounting or because of exposure to the outside elements, can destroy peripheral seals between the panels and detract from the appearance of the covering. Such irregularities are especially noticeable in panels formed with simulated "perfection" shake, which have a relatively uniform appearance. Because of the uniformity in such perfection shake panels, difficulties also have been incurred in forming corners with the wall covering without detracting from the realistic and aesthetic appearance of the installation.